Trees look pretty in a garden; it gives the eye something to look at no matter the season. Your garden can look attractive all year long no matter what the weather. You can keep trees a lot more pruned and smaller than you think if you pick the right ones for your area. Using small trees in your garden will improve air quality, protect against bad weather, and even help change the climate in the garden for better growth – such as in super-sunny and hot areas that don’t have any type of shade.

Trees help reduce urban air pollution, absorb carbon dioxide, and help cool places that are too hot due to trapped gases in urban areas. You can basically use small trees in your garden to change the climate and improve the air quality substantially. Trees are able to clean the air and absorb harmful airborne particles and gaseous pollutants. Toxins such as nitrogen oxides, ammonia and sulphur dioxide through their leaves, bark and roots.

Trees can block the suns rays from anything within their shade. That prevents solar radiation from heating the ground, the surrounding buildings and surfaces as well as cooling the local area. 

Trees, like all plants, use a large percentage of the radiation that they intercept to evaporate water from within their leaves (Monteith and Unsworth, 1990). This process, known as evapotranspiration, cools them down and reduces the amount of heat available to warm the air around them.

Plan your garden to create perfect microclimates. Covering beds with plastic helps dry out and warm up soil. Plant small trees and try to group them. Water-filled plastic bottles will absorb heat during the day and release it at night. Grow cool-season crops in the shade of taller plants. Windbreaks made from willow or hazel filter harmful gusts. 

Trees and vegetation also provide cooling through evaporation of rainfall collecting on leaves and soil. Research shows that urban forests have temperatures that are on average 2.9°F lower than un-forested urban areas. 

TREES CAN HELP!- They absorb water and then release it as water vapour through their leaves in a process called evapotranspiration, which produces a cooling effect. Trees also provide shade for the ground and buildings, resulting in further cooling and less energy usage.

Small trees in your garden will help absorb rainwater so that it keeps your garden from getting too wet and flooding. The leaves collect, stop, and slow the rain down, preventing soil erosion during bad weather cycles. Green infrastructure techniques, such as green roofs and rain gardens, can help to reduce the volume of runoff and improve the quality of the water that is discharged into the environment.

Build a soakaway – A soakaway is essentially a hole in the ground filled with stones or specially designed plastic crates. They help prevent flooding and reduce stress on the drain network. Soakaways are built underground and are connected to a downpipe, which carries rainfall away from the property. Try install rainwater butts for collecting roof rain runoff.

In general, when the rate of infiltration and transmission through the soil is higher, the volume of runoff is lower. As a result of low infiltration and transmission rates, fine textured soils, such as clay, produce a higher runoff volume than do coarse textured soils, such as sand. 

Trees that absorb a lot of water. Red maple (zones 3-9), Weeping willow (zones 6-8), Ash (zones 3-9), Oriental arborvitae (zones 6-11), Black gum (zones 4-9), White cedar (zones 4-8), River birch (zones 3-9), Bald cypress (zones 5-9).

If you live in a very hot area where the sun is very strong and there isn’t very much rain or cool weather, it can be hard to grow food in your garden or even use your garden or yard. Small trees placed strategically can provide shade and adjust the climate in your garden naturally. Build trellises or pergola’s planted with fast growing wisteria’s, honeysuckle or ivy.

Plant leafy trees – The best trees for garden shade are those that have thick leaves and large branches. They work best when planted with space to grow, which makes them ideal for creating shady spots away from the house.

For the most natural way to create shade in your backyard, consider planting new trees in ideal locations but be aware of growing roots and branches. You may purchase a tree that has already grown in height. The young tree may not provide a lot of shade at first but will grow through the years and expand the amount of shade provided for the backyard. 

The best way for a garden to face for sunlight and how important is it which way your garden faces
OK, a quick breakdown of the sunlight that gardens or yards receive throughout the year is as follows:

• Gardens that face north receive the least sunlight and can be damp. Not good.
• Gardens that face south receive the most sunlight. The ideal position.
• Gardens that face east receive sunlight in the morning.
• Gardens that face west receive sunlight in the late afternoon and evening.

Some plants are delicate and others are much stronger. Small trees can help block the wind strategically in your garden and force the wind to go around your garden if you place the trees properly. That will help protect delicate garden plants and fruit bearing plants. Place windbreaks at right angles to the prevailing wind direction. The best windbreaks temper the wind by allowing some air to pass through. This will reduce the intensity of the wind along the sides of the barrier. Choose windbreak plants that are multiple stemmed or densely branched to the ground. Also use a wind break or shelter – this is often very effective where it’s possible. Tie up your plants well and adjust watering routines to reduce the impact of the wind. Choose plants that are better adapted to the wind.
Plants that are good against the wind can include tall plants with flexible stems that bend without breaking, such as fennel and grasses, also have good wind-resistance. Conversely, sturdy, low-growing plants such as Alchemilla mollis are able to withstand a bit of a battering to. It’s also a good idea to create a living windbreak by planting a hedges facing the prevailing wind. This will have the benefit of reducing wind speed, and so protecting other plants in the garden and providing a shelter for wildlife. Suitable hedging plants include berberis, hawthorn, oleaster (also called Russian olive, or trebizond date) and sea buckthorn or privet. You can create a garden sized shelter belt using a mixture of small trees and shrubs pruned into tall columns. These will slow the wind down.

So here’s the physics bit, for every 1m of height, you should get 2m of wind break.